From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754443AbbDQPbp (ORCPT ); Fri, 17 Apr 2015 11:31:45 -0400 Received: from bh-25.webhostbox.net ([208.91.199.152]:37764 "EHLO bh-25.webhostbox.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754110AbbDQPbm (ORCPT ); Fri, 17 Apr 2015 11:31:42 -0400 Date: Fri, 17 Apr 2015 08:31:36 -0700 From: Guenter Roeck To: Jens Axboe Cc: linux-kernel@vger.kernel.org, Chong Yuan , Wenbo Wang Subject: Re: Upstream kernel fails to run on qemu-sparc64 due to commit 889fa31f0 (blk-mq: reduce unnecessary software queue looping) Message-ID: <20150417153136.GA11202@roeck-us.net> References: <20150417063220.GA2871@roeck-us.net> <20150417133204.GA29300@roeck-us.net> <55311803.9030105@fb.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <55311803.9030105@fb.com> User-Agent: Mutt/1.5.23 (2014-03-12) X-Authenticated_sender: guenter@roeck-us.net X-OutGoing-Spam-Status: No, score=-1.0 X-CTCH-PVer: 0000001 X-CTCH-Spam: Unknown X-CTCH-VOD: Unknown X-CTCH-Flags: 0 X-CTCH-RefID: str=0001.0A020201.5531275D.0242,ss=1,re=0.000,recu=0.000,reip=0.000,cl=1,cld=1,fgs=0 X-CTCH-Score: 0.000 X-CTCH-ScoreCust: 0.000 X-CTCH-Rules: X-CTCH-SenderID: linux@roeck-us.net X-CTCH-SenderID-Flags: 0 X-CTCH-SenderID-TotalMessages: 2 X-CTCH-SenderID-TotalSpam: 0 X-CTCH-SenderID-TotalSuspected: 0 X-CTCH-SenderID-TotalConfirmed: 0 X-CTCH-SenderID-TotalBulk: 0 X-CTCH-SenderID-TotalVirus: 0 X-CTCH-SenderID-TotalRecipients: 0 X-AntiAbuse: This header was added to track abuse, please include it with any abuse report X-AntiAbuse: Primary Hostname - bh-25.webhostbox.net X-AntiAbuse: Original Domain - vger.kernel.org X-AntiAbuse: Originator/Caller UID/GID - [47 12] / [47 12] X-AntiAbuse: Sender Address Domain - roeck-us.net X-Get-Message-Sender-Via: bh-25.webhostbox.net: mailgid no entry from get_relayhosts_entry X-Source: X-Source-Args: X-Source-Dir: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Jens, On Fri, Apr 17, 2015 at 08:26:11AM -0600, Jens Axboe wrote: > >> > >As additional information: > > > >+ * Set the map size to the number of mapped software queues. > >+ * This is more accurate and more efficient than looping > >+ * over all possibly mapped software queues. > >+ */ > >+ map->map_size = hctx->nr_ctx / map->bits_per_word; > > > >On my system, hctx->nr_ctx is 1, and map->bits_per_word is 8. > >Thus map->map_size is set to 0, which doesn't make much sense. > > > >The system comes up if I replace the above code with > > map->map_size = DIV_ROUND_UP(hctx->nr_ctx, map->bits_per_word); > > > >I have no idea if that is the correct fix, though. > > Ugh, yes indeed, looks like the <= was lost from a previous patch. Now I > wonder why it I didn't see any hangs with this... Thanks for reporting, I'll > get a fix in today. > Assuming that nr_ctx reflects the number of (online) CPUs, my guess is that you may have a multiple of bits_per_word CPUs in your system. Guenter